I have an older SSD in my laptop full of static data, mostly FLAC and a few zip files, there's very few files less than 10MB and likewise writes are weekly rather than multiple per second. I'm reluctant to buy a new, legacy disk to get more space because I move the laptop round a lot and my experience with legacy disks and bicycles is that they are a bad combination.
Looking at "advantages of BTRFS" "different filesystems" and HowToGeek I can't help thinking that ext2fs is likely to be the most space-efficient filesystem. It's not journalling, which is good for this application, and it's ok with large files. I don't think speed actually matters here, since the SSD is wildly faster than the music player needs.
Is there a better filesystem for this than EXT2? Can I format an SSD as one of the read-only CDFS-style formats, and would that get me more usable space?